In this photograph taken on February 18, 2016, Pakistani children ride on swings in the predominantly Pashtun Korangi District of Karachi. In a rundown district of Karachi, Rabia balks at a neighbour's proposal to vaccinate her children, demonstrating one of the biggest hurdles to eradicating polio in Pakistan by the end of the year: confused and frightened parents. (Photo by Asif Hassan/AFP Photo)

An Afghan boy looks through the scope of a toy gun, as other children ride on swings during the first day of the Muslim holiday of Eid al-Fitr, which marks the end of the holy month of Ramadan, in Kabul, Afghanistan June 25, 2017. (Photo by Omar Sobhani/Reuters)

A woman rides the world's longest urban zip line, with a speed of up to 80 kilometers per hour on a one kilometer run from 170 meter to ground level, in the Marina district of Dubai, United Arab Emirates, Tuesday, December 5, 2017. (Photo by Kamran Jebreili/AP Photo)

Sandra Brown, 40, rides the Skyslide on the 69th and 70th floors of the U.S. Bank Tower which is attached to the OUE Skyspace LA observation deck in downtown Los Angeles, California, U.S. June 20, 2016. (Photo by Lucy Nicholson/Reuters)

A Cambodian villager rides a buffalo during the Pchum Ben festival, the festival of death, at Vihear Suor village in Kandal province on October 1, 2016. Thousands of Cambodians descended on the small village northeast of the capital on October 1 to cheer on the annual water buffalo race that marks the end of the 15-day festival for the dead. (Photo by Chor Sokunthea/AFP Photo)

Rani rides home with her father on the back of his bicycle on March 6, 2017 in Khulna division, Bangladesh. Rani, who is now 16, was under pressure to marry a boy when she was 14-years-old despite the reluctance of Rani and her father, Abdul. (Photo by Allison Joyce/Getty Images)

A kid wearing rollerblades hitches a ride via motorbike, in Port-au-Prince, Haiti, Sunday, October 25, 2015. The country held the first-round presidential vote Sunday. Haitians chose between 54 presidential hopefuls and a slew of legislative and municipal candidates. (Photo by Ricardo Arduengo/AP Photo)

Members of the New Forest Hunt ride off from Boltons Bench for the annual Boxing Day hunt in Lyndhurst, southern England, Britain December 26, 2016. Since a ban stopped fox hunting with hounds, hunts continued with dogs chasing down a pre-laid scented trail instead of a fox. (Photo by Luke MacGregor/Reuters)